Circuit member and mounting structure having hollow space, and method for producing the mounting structure

Abstract

A circuit member including: an element having a functional region; a tabular cover disposed opposite to the functional region; and a rib formed to surround the functional region, for providing a space between the functional region and the cover. The cover includes a sheet S having a thickness of 100 μm or less. The sheet S has a tensile elastic modulus Es at 175° C. of 10 GPa or more. The tensile elastic modulus Es at 175° C. of the sheet S is preferably 20 GPa or more.

1 . A circuit member, comprising:
 an element having a functional region;   a tabular cover disposed opposite to the functional region; and   a rib formed to surround the functional region, for providing a space between the functional region and the cover,   the cover including a sheet S having a thickness of 100 μm or less,   the sheet S having a tensile elastic modulus Es at 175° C. of 10 GPa or more.   
     
     
         2 . The circuit member of  claim 1 , wherein the tensile elastic modulus Es at 175° C. of the sheet S is 20 GPa or more. 
     
     
         3 . The circuit member of  claim 1 , further comprising an adhesion layer A provided on at least part of an abutment surface between the element and the rib, and/or on at least part of an abutment surface between the cover and the rib. 
     
     
         4 . The circuit member of  claim 3 , wherein the adhesion layer A has a tensile elastic modulus Ea at 175° C. of 10 MPa or more. 
     
     
         5 . The circuit member of  claim 3 , wherein the adhesion layer A has a glass transition temperature Tga of 80° C. or more. 
     
     
         6 . The circuit member of  claim 3 , wherein the adhesion layer A contains a thermosetting resin in a cured state. 
     
     
         7 . The circuit member of  claim 3 , wherein:
 the adhesion layer A is provided on at least part of the abutment surface between the cover and the rib; and   under a temperature condition equal to or lower than the glass transition temperature Tga of the adhesion layer A,   the adhesion layer A has a linear expansion coefficient CTEa of 60 ppm/° C. or less, and   a difference between the linear expansion coefficient CTEa of the adhesion layer A and a linear expansion coefficient CTEs of the sheet S is 50 ppm/° C. or less.   
     
     
         8 . The circuit member of  claim 1 , wherein a material of the sheet S is at least one selected from the group consisting of ceramics, silicon, glass, glass fiber-reinforced resin, and metal. 
     
     
         9 . The circuit member of  claim 8 , wherein the material of the sheet S is the glass. 
     
     
         10 . The circuit member of  claim 8 , wherein the material of the sheet S is the glass fiber-reinforced resin. 
     
     
         11 . The circuit member of  claim 1 , further comprising a resin encapsulant encapsulating the circuit member. 
     
     
         12 . A sheet material for forming the cover of  claim 1 . 
     
     
         13 . The sheet material of  claim 12 , further comprising an adhesion layer AP. 
     
     
         14 . The sheet material of  claim 13 , wherein the adhesion layer AP contains a thermosetting resin in an uncured or semi-cured state. 
     
     
         15 . The sheet material of  claim 14 , wherein
 under a temperature condition equal to or higher than room temperature and equal to or lower than a curing temperature of the adhesion layer AP,   the adhesion layer AP has a storage shear modulus Ga′ of 0.05 to 10 MPa, and   a ratio: Ga″/Ga′ of a loss shear modulus Ga″ of the adhesion layer AP to the storage shear modulus Ga′ is 0.1 to 2.0.   
     
     
         16 . A mounting structure, comprising
 a first circuit member, and a second circuit member mounted on the first circuit member,   the second circuit member comprising:   an element having a functional region;   a tabular cover disposed opposite to the functional region; and   a rib formed to surround the functional region, for providing a space between the functional region and the cover,   the cover including a sheet S having a thickness of 100 μm or less,   the sheet S having a tensile elastic modulus Es at 175° C. of 10 GPa or more.   
     
     
         17 . The mounting structure of  claim 16 , further comprising a resin encapsulant encapsulating the second circuit member. 
     
     
         18 . A method for producing a mounting structure, comprising steps of:
 (i) preparing a first circuit member and a second circuit member; and   (ii) mounting the second circuit member on the first circuit member,   the second circuit member comprising:   an element having a functional region;   a tabular cover disposed opposite to the functional region; and   a rib formed to surround the functional region, for providing a space between the functional region and the cover;   the cover including a sheet S having a thickness of 100 μm or less,   the sheet S having a tensile elastic modulus Es at 175° C. of 10 GPa or more.   
     
     
         19 . The method for producing a mounting structure of  claim 18 , wherein the second circuit member prepared in the step (i) includes a resin encapsulant encapsulating the second circuit member. 
     
     
         20 . The method for producing a mounting structure of  claim 18 , further comprising a step of: (iii) encapsulating the second circuit member mounted on the first circuit member, with a resin encapsulant.